[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 041244
SWODY1
SPC AC 041242

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0742 AM CDT THU MAY 04 2006

VALID 041300Z - 051200Z

...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF SW AND S CNTRL
TX...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF SRN/CNTRL AND SW
TX...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE ARKLATEX AND TN VLY TO
THE SRN APLCNS...

...SYNOPSIS...
WEAK...SLOWLY PROGRESSIVE SPLIT FLOW PATTERN WILL PREVAIL THIS
PERIOD ACROSS THE LWR 48.  SEVERE TSTM CHANCES SHOULD REMAIN
CONFINED TO THE DIFFLUENT SRN BRANCH THAT WILL EXTEND E/NE INTO THE
SRN PLNS...DOWNSTREAM FROM CNTRL/SRN CA CLOSED LOW.

AT LWR LEVELS...EXPANSIVE SURFACE RIDGE IN WAKE OF NRN STREAM LOW
NOW CROSSING ONTARIO WILL CONTINUE TO PRESS S/SE INTO THE SRN
PLNS...THE MID/LWR MS VLYS AND THE ERN GRT LKS.  EFFECTIVE COLD
FRONT MARKING LEADING EDGE OF RIDGE WILL BE SHUNTED S INTO CNTRL
TX/SE OK AND CNTRL AR TODAY BY COMPOSITE OUTFLOW FROM OVERNIGHT
MCSS.  FARTHER E...EXPECT WEAK WARM FRONT THAT HELPED SPAWN STORMS
IN MO/AR AND THE LWR TN MS VLY YESTERDAY WILL REDEVELOP E TOWARD THE
SRN APLCNS AND WEAKEN.

...S CNTRL TX INTO SE NM...
DISSIPATING NRN/CNTRL TX MCS HAS LEFT A WELL-DEFINED OUTFLOW
BOUNDARY THAT EXTENDS FROM THE ERN/SRN HILL COUNTRY W ACROSS THE
EDWARDS PLATEAU TO NEAR MAF.  THE WRN PART OF THE BOUNDARY MAY EDGE
A BIT N TODAY BEFORE BEING INTERCEPTED BY SYNOPTIC COLD FRONT NOSING
S FROM NEAR LBB.  THE COMBINED BOUNDARIES SHOULD MORE OR LESS STALL
ALONG ROUGHLY A WNW/ESE AXIS FROM NEAR MAF TO NEAR SJT ...AND LIKELY
WILL SERVE AS A FOCUS FOR NEW STORM DEVELOPMENT LATE TODAY.

SATELLITE LOOPS SUGGEST PRESENCE OF AN UPR LEVEL IMPULSE NOW OVER SW
NM/NRN SONORA THAT SHOULD REACH W CNTRL AND SW TX BY LATE IN THE
DAY.  SATELLITE ALSO SUGGESTS THAT HEATING WILL BE STRONG IN WAKE OF
MCS DEBRIS FROM THE HILL COUNTRY W INTO THE PERMIAN BASIN/SE NM. 
QUALITY BOUNDARY LAYER MOISTURE IS ALREADY PRESENT AS FAR W AS
DRT/SJT...AND SOME WWD ADVECTION OF MOISTURE LIKELY WILL OCCUR INVOF
STALLING FRONT/OUTFLOW BOUNDARY THROUGH THE DAY.  THUS... EXPECT
THAT STRONG INSTABILITY WILL DEVELOP...WITH MLCAPE OF 2000 TO 3000
J/KG LIKELY BY PEAK HEATING.

COMBINATION OF STRONG INSTABILITY...WEAK BUT INCREASING LARGE SCALE
ASCENT...AND 30+ KT WSWLY MID LEVEL FLOW SHOULD SUPPORT SUPERCELLS
WITH BOTH VERY LARGE HAIL AND HIGH WIND.  IN ADDITION...ASSUMING
THAT THE SURFACE BOUNDARIES DO INDEED BECOME NEARLY
STATIONARY...POTENTIAL WILL ALSO EXIST FOR TORNADOES WITH ANY
DISCRETE RIGHT-MOVING STORMS THAT MOVE ALONG THE FRONT.

GOOD MOISTURE AVAILABILITY...DIURNAL STRENGTHENING OF MODERATE SLY
LLJ...AND EWD PROGRESSION OF SAME AS UPR IMPULSE CONTINUES EWD ALL
SUGGEST THAT THE TX STORMS WILL EVOLVE INTO A LARGE COMPLEX.  THIS
SYSTEM SHOULD MOVE E/SE ACROSS S CNTRL AND PERHAPS SE TX THROUGH
EARLY FRIDAY.

...ARKLATEX/NRN GULF STATES/TN VLY...
MODERATE TO STRONG SURFACE HEATING SHOULD OCCUR FROM THE ARKLATEX  E
INTO THE PARTS OF MS...AL AND GA TODAY...S AND E OF AFOREMENTIONED
MCS OUTFLOW BOUNDARIES.  SYNOPTIC SCALE FORCING FOR ASCENT WILL BE
WEAK.  BUT COMPOSITE RADAR DATA SUGGEST PRESENCE OF SEVERAL MCVS
EMBEDDED WITHIN THE ERN OK/N TX CONVECTIVE COMPLEXES THAT LIKELY
WILL SERVE TO ENHANCE MESOSCALE ASCENT AS THEY CONTINUE GENERALLY
EWD.  THIS ENHANCEMENT MAY BE MAXIMIZED FROM CNTRL AR INTO NRN
MS/AL...WHERE THE SYSTEMS WILL INTERACT WITH REMNANT WARM FRONT. 
FOCUSED UPLIFT SHOULD ALSO OCCUR ALONG COLD FRONT SETTLING SE FROM
KY INTO TN.

MODEST /20-25 KT/ W TO WNWLY MID LEVEL FLOW WILL LIMIT STORM
ORGANIZATION AND LONGEVITY.  BUT GIVEN EXPECTED DEGREE OF
INSTABILITY /SBCAPE OF 1500-2000 J PER KG/ AND FORCING FOR ASCENT
PROVIDED BY MCVS...EXPECT INTENSIFICATION OF EXISTING STORMS IN
WEAKLY CAPPED ENVIRONMENT BY EARLY AFTERNOON.  THIS ACTIVITY COULD
YIELD LOCALLY DAMAGING WIND AND MARGINALLY SEVERE HAIL AS STORMS
MOVE/DEVELOP E TO THE SRN SLOPES OF THE APLCNS THROUGH THE REMAINDER
OF THE DAY.  GIVEN LARGELY STATIC PATTERN AND PERSISTENT MOIST
INFLOW...THE WIDESPREAD CONVECTION MAY SUPPORT DEVELOPMENT OF AN
ADDITIONAL MCV TONIGHT OVER THE LWR TN VLY...WITH AN ATTENDANT
THREAT FOR MARGINALLY SEVERE HAIL/WIND AND HEAVY RAIN.

...OH VLY TO THE LWR GRT LKS...
MOISTURE RETURN WILL BE SCANT AHEAD OF TRAILING COLD FRONT
ASSOCIATED WITH NRN STREAM IMPULSE IN ONTARIO. THIS WILL LIMIT 
CAPE TO AOB 500 J/KG.  BUT FRONTAL UPLIFT AND FORCING FOR ASCENT ON
SRN EDGE OF ONTARIO TROUGH MAY BE SUFFICIENT FOR SCATTERED AFTERNOON
TSTMS ACROSS NY/PA.  DEEPLY MIXED BOUNDARY LAYER WITH SIZABLE
TEMPERATURE/DEW POINT SPREADS COULD SUPPORT LOCALLY DAMAGING GUSTS. 
FARTHER SW ALONG THE FRONT...UVV SHOULD BE WEAKER.  BUT WIDELY
SCATTERED STORMS SHOULD DEVELOP SW INTO THE LWR OH VLY BY EARLY
EVENING...WHERE THERMODYNAMIC SETUP COULD SUPPORT A COUPLE CELLS
WITH MARGINALLY SEVERE HAIL.

...GREAT BASIN...
COLD FRONT ASSOCIATED WITH CA TROUGH WILL LINGER OVER THE CNTRL GRT
BASIN/CNTRL RCKYS TODAY.  THE BOUNDARY MAY ONCE AGAIN BE A FOCUS FOR
WIDELY SCATTERED LATE AFTERNOON STORMS.  MOISTURE WILL BE
LIMITED...BUT VERY STEEP LAPSE RATES BENEATH MODERATE SWLY MID LEVEL
FLOW ON E SIDE OF TROUGH MAY PROMOTE DEVELOPMENT OF A FEW CELLS WITH
HAIL/WIND GUSTS APPROACHING/BRIEFLY EXCEEDING SEVERE LIMITS.

..CORFIDI/GRAMS.. 05/04/2006